Herrenknecht’s advanced hard rock tunnelling technology has made strides, breaking through in Norway.
The achievement marks an important milestone for the consideration of tunnelling technologies in hard rock geologies, which have traditionally favoured drill and blast construction.
During the project, four Herrenknecht tunnel boring machines (TBM) were used to excavate twin 20 km tunnels from the municipality of Ski to Oslo.
To overcome the challenge of tunnelling through the region’s hard Norwegian gneiss rock, which has up to 300 MPa compressive strength, Herrenknecht advanced the design of the TBMs’ disc cutters.
The 19 inch (483 mm) diameter cutters were made of special steel, each weighing up to 372 kg and applied to the rock with up to 32 t of pressure.
Up to 50 cutter experts were required to refurbish approximately 8,000 worn disc cutters for reuse across the life of the project.
The Norwegian Government’s railway service agency, Bane NOR, commissioned the Acciona-Ghella Joint Venture (JV) to construct the main part of the tunnel.
“Even the tiniest improvement to the discs counts,” said Acciona-Ghella JV Project Director Fernando Vara.
“If optimal cutter management allows us to complete just one more tunnel ring per day and machine, this ultimately adds up to put us two to three months ahead of the planned project time.”
With regular maintenance and teamwork, peak advance performance rates of 155 m per week were achieved.
An in-depth article on this project was featured in the Summer 2018 edition of Trenchless International. To view the magazine on your PC, Mac, tablet, or mobile device, click here.
For more information visit the Herrenknecht website.
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